Method of calibrating an ophthalmic processing device, machine programmed therefor, and computer program

ABSTRACT

The present invention is directed to a method of calibrating drill depth of an ophthalmic processing device. A number of drill cycles are selected for drilling an expected number of holes in a lens blank. The selected number of drill cycles is performed. The drill depth of each consecutive drill cycle varies incrementally. An actual number of locations the drill bit contacted the lens blank during the drill cycles is compared to the expected number of holes. The drill depth is adjusted depending on the compared values. A method of calibrating drill hole size is also disclosed.

COMPUTER PROGRAM LISTING APPENDIX

A computer program listing appendix is submitted herewith on compactdisc recordable (CD-R) as Appendix A, and the material thereon isincorporated herein by reference. Duplicate copies of Appendix A areprovided as Copy 1 and Copy 2. Copy 1 and Copy 2 are identical.

The files contained on Copies 1 and 2 are as follows:

File Name: Size in Bytes: Date of CD Creation: DrillCalibration 6,039 14Nov. 2006

FIELD OF THE INVENTION

The present invention is directed to a method of calibrating drill depthof an ophthalmic processing device. A number of drill cycles areselected for drilling an expected number of holes in a lens blank. Theselected number of drill cycles is performed. The drill depth of eachconsecutive drill cycle varies incrementally. An actual number oflocations the drill bit contacted the lens blank during the drill cyclesis compared to the expected number of holes. The drill depth is adjusteddepending on the compared values. A method of calibrating drill holesize is also disclosed.

BACKGROUND OF THE INVENTION

Prescription eyeglass lenses are curved in such a way that light iscorrectly focused onto the retina of a patient's eye, improving vision.Such lenses are formed from glass or plastic lens “blanks” havingcertain desired properties to provide the correct prescription for thepatient. The blanks are usually circular and of substantially largerdimension compared to the relatively smaller finished lenses assembledinto eyeglass frames. Therefore, a lens blank must be edged to fit aneyeglass frame selected by the patient.

Ophthalmic laboratory technicians cut, grind, edge, and polish blanksaccording to prescriptions provided by dispensing opticians,optometrists, or ophthalmologists. The specifications include thepatient's full prescription, including: 1) the total power the finishedlens must have; 2) the strength and size of any segments, if needed(i.e. multifocal lenses); 3) the power and orientation of any cylindercurves; and 4) the location of the optical center and any inducted prismthat may be needed.

In addition, the large diameter blank is sized and shaped to fit intothe frame selected by the patient. The lens blank may be shaped using anedger, such as the edger disclosed in U.S. Pat. No. 6,203,409 to Kennedyet al., the disclosure of which is incorporated herein by reference. Theblank is edged so that the periphery of the finished lenses fit into theopenings on the frames.

Edging of a lens blank typically requires the application of a block toa surface thereof. The block is releaseably secured to a clamp assembly,so that rotation of the clamp assembly causes corresponding rotation ofthe lens blank. As the blank is rotated, the periphery of the blank maybe cut to a desired size using a router tool. The blank may be eitherground or cut. Wet edgers use diamond-impregnated wheels with differentabrasive grits to grind the lens material. A coolant is sprayed on thewheels during edging to reduce heat. Dry edgers use carbide steel ordiamond blades mounted on the spindle of a motor to shave the lens. Thelens periphery may also be polished using a polishing tool. Some edgersare also able to form a bevel about the periphery of the lens.

Information relating to the size and shape of the lens needed for aparticular frame (i.e. trace data) may be generated, and subsequentlytransmitted to the edger. Such trace data may be provided by framemanufacturers, or generated by a tracer machine. Trace data may bedownloaded and/or transmitted to a storage medium in a control system,such as a central processing unit, in communication with the edger. Theedger processes the edge of the lens blank to create an edge profileaccording to the trace data. The finished lens may then be assembledwith the selected eyeglass frames.

In order to improve efficiency, some edgers use CNC (Computer NumericControl) technology whereby a computer controls the lens processingequipment by following encoded commands. The commands are based oninformation from frame tracings or internal lens probes and the user.Information relating to the size and shape of the lens needed for aparticular frame (i.e. trace data) may be generated, and subsequentlytransmitted to the edger. The trace data may be stored in the storagemedium and recalled by the control system as needed.

Some lenses require that the lens contain drill features in the surfaceof the lens. For example, some frame assemblies require that one or moreholes be drilled in the lenses, particularly lenses to be used inrimless style frames. Several factors to consider when determining thehole position include the horizontal and vertical coordinates, lens basecurve, wrap angle, and the mounting's pantoscopic tilt. Hand drilling isused by some laboratories. Other laboratories use a drill press.

Typically, one drill bit is used to cut holes of varying sizes. In orderto provide proper drill hole size, many conventional techniques requirea technician to drill holes into a lens blank, and then make anestimation of the hole size correction needed. This is often a tediousand time consuming operation. In addition, accurate drill depth isrequired for optimal functioning of a lens drilling mechanism. Holesmust typically be drilled completely through the lens blank. It is notalways obvious to the technician that an adjustment is needed to achieveproper drill depth, particularly when drilling lens blanks having arelatively high wrap, such as frames having a curvature greater than 6diopters.

SUMMARY OF THE INVENTION

The present invention is directed to a method of calibrating drill depthof an ophthalmic processing device. An ophthalmic lens blank and aprocessing device are provided. The processing device has a drill bitfor drilling holes in the lens blank. At least one of the drill bit andthe lens blank is moveable toward and away from the other during a drillcycle by a predetermined distance defining a drill depth. A number ofdrill cycles are selected for drilling an expected number of holes inthe lens blank. The selected number of drill cycles is performed by theprocessing device. The drill depth of each consecutive drill cyclevaries incrementally. An actual number of locations the drill bitcontacted the lens blank during the drill cycles is compared to theexpected number of holes. Drill depth is decreased if the actual numberof holes is more than the expected number of holes. Drill depth isincreased if the actual number of holes is less than the expected numberof holes.

The present invention is also directed to a method of calibrating anophthalmic processing device used to cut holes of variable diameter in alens blank. A lens blank and a processing device for drilling holes inthe lens blank during drill cycles are provided. A base hole size havinga predetermined diameter is selected. A number of drill cycles forforming a corresponding number of holes having expected diameters thatvary incrementally is selected. The selected number of drill cycles isperformed. The actual diameters of the holes formed during the performeddrill cycles are compared to the predetermined diameter. The drill cyclethat formed the hole having the actual diameter corresponding to thepredetermined diameter is selected. The expected diameter of theselected drill cycle is adjusted to conform to the predetermineddiameter. A processing device programmed to drill holes in an ophthalmiclens blank is also disclosed. The device includes a processing devicehaving a drill bit for drilling holes in a lens blank and a carriage forretaining the lens blank. One of the drill bit and the carriage aremoveable toward and away from each other during a drill cycle. A centralprocessing unit operably associated with the processing device controlsoperation thereof. A user interface in communication with the centralprocessing unit receives and transmits commands from a user to thecentral processing unit. A computer program stored on a medium incommunication with the central processing unit comprises a plurality ofdrilling instruction sets and a calibration instruction set. Each of thedrilling instruction sets operably causes one of the drill bit and thecarriage to move toward the other by a predetermined distance defining adrill depth. The drill depth associated with each drilling instructionset varies. The calibration instruction set adjusts each of the drilldepths by a selected amount corresponding to a command received from theuser interface.

A processing device programmed to drill holes in an ophthalmic lensblank is also disclosed. The device includes a processing device havinga drill bit for drilling holes in a lens blank of variable size. Acentral processing unit operably associated with the processing devicecontrols operation thereof. A user interface in communication with thecentral processing unit receives and transmits commands from a user tothe central processing unit. A computer program stored on a medium incommunication with the central processing unit includes a plurality ofdrilling instruction sets, and a calibration instruction set. Each ofthe drilling instruction sets operably causes the processing device toform a hole having a predetermined diameter defining a hole size. Thehole sizes associated with each drilling instruction set varies. Thecalibration instruction set adjusts each of the hole sizes by a selectedamount corresponding to a command received from the user interface.

The present invention also relates to a computer program stored on amedium for use in a drilling process employing a lens blank and aprocessing device. The computer program comprises: a) a plurality ofdrilling instruction sets, each of the drilling instruction setsoperably causes one of a lens blank and a drill bit associated with aprocessing device to move toward the other by a predetermined distancedefining a drill depth, wherein the drill depth associated with eachdrilling instruction set varies; and b) a calibration instruction setthat adjusts each of the drill depths by a selected amount correspondingto a command received from a user interface in communication with theprocessing device.

The present invention also relates to a computer program stored on amedium for use in a drilling process employing a lens blank and aprocessing device, the computer program comprising: a) a plurality ofdrilling instruction sets, each of the drilling instruction setsoperably causing a processing device to form a hole having apredetermined diameter defining a hole size, wherein the hole sizesassociated with each of the drilling instruction sets varies; and b) acalibration instruction set that adjusts each of the hole sizes by aselected amount corresponding to a command received from a userinterface in communication with the processing device.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an edger device for use in a calibrationprocess according to the present invention;

FIG. 2 is a perspective view of a drilling mechanism for use in adrilling process according to the present invention;

FIG. 3 is a perspective view of a drill bit usable on the drillingmechanism of FIG. 2;

FIG. 4 is a fragmentary sectional view of an ophthalmic lens blank anddrill bit with holes in the lens blank shown in phantom;

FIG. 5 is a chart showing processing steps for a calibration processaccording to the present invention;

FIG. 6 is a view of a display screen showing input fields for a drilldepth calibration method according to the present invention;

FIG. 7A is a chart showing a first processing step according to thepresent invention;

FIG. 7B is a chart showing a second processing step according to thepresent invention;

FIG. 7C is a chart showing a third processing step according to thepresent invention;

FIG. 8 is a chart showing processing steps for a calibration processaccording to another embodiment; and

FIG. 9 is a view of a display screen showing input fields for a drillhole size calibration method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a method of calibrating drill depthof an ophthalmic processing device. As known in the art, drill featuresare sometimes required on a finished ophthalmic lens blank, such aslenses for rimless glasses. Processing of an ophthalmic lens blank maytherefore require the formation of one or more holes having a particulardiameter.

An edger and processing device 10 capable of forming drill features isbest shown in FIG. 1. Suitable edger and processing devices areavailable from National Optronics of Charlottesville, Va., such as the7E Patternless Edger machine. Processing device 10 may include amechanism for edging the lens blank, and a drill mechanism 12 forforming drill features, as shown in FIG. 2.

A central processing unit, or “CPU”, (not shown) is provided, preferablyas an internal component of processing device 10. However, the CPU mayalso be external to processing device 10. The CPU is operably associatedwith processing device 10 and controls operation thereof. The CPUincludes a storage medium. A computer program is stored on the mediumand in communication with the CPU. Processing instructions, trace data,and other information relating to processing and edging may be stored inthe storage medium and recalled by the CPU.

Drill mechanism 12 includes a pivot motor assembly 14, a drill motorassembly 16, an upper drill switch assembly 18, a lower drill switchassembly 20, a drill spindle assembly 22, and a drill bit 24. As shownin FIGS. 2 and 3, drill bit 24 may be provided on a shaft 26 which issecured to drill spindle assembly 22. Shaft 26 may be secured to drillspindle assembly 22 via a collet nut 28 or other fastener. Drill spindleassembly 22 is coupled to drill motor assembly 16 via a drive belt (notshown) disposed under a cover plate 30. Drill motor assembly 16 therebycauses rotation of drill spindle assembly 22, and thus drill bit 24 viarotation of the associated drive belt.

In addition, drill spindle assembly 22 may pivot into a drillingposition adjacent a lens blank to be drilled, or away from the lensblank when drilling mechanism 12 is not processing the lens blank, suchas when processing device 10 is edging the lens blank. Drill spindleassembly 22 may be secured to a support arm 32, which is pivotablyconnected to and supported by a support bracket 34. Support arm 32, andtherefore drill spindle assembly 22 and drill bit 24, may be pivotedtoward and away from a drilling position adjacent the lens blank to bedrilled via pivot motor assembly 14. For example, support arm 32 may berotated about support bracket 34 in a counterclockwise direction about180° away from the drilling position shown in FIG. 2.

Upper and lower drill switch assemblies 18, 20 may include sensors ormechanical switches which are activated by support arm 32. Switchassemblies 18, 20 are coupled to the CPU. When support arm 32 is in thedrilling position, as shown in FIG. 2, upper drill switch assembly 18may be activated and a signal transmitted to the CPU via associatedwiring, which indicates that drill bit 24 is in the drilling positionand ready for a drill cycle. Support arm 32 may be rotated away from thedrilling position to a secondary position when drilling is not beingperformed. When support arm 32 is in the secondary position, lower drillswitch assembly 20 may be activated and a signal transmitted to the CPUvia associated wiring, which indicates that the drill spindle assembly22 is pivoted away from the lens blank processing area. Edging or otherprocessing of the lens blank may then be initiated, or the lens removedfrom processing device 10.

Preferably, when drill spindle assembly 22 is disposed in the drillingposition, proximate the lens blank being processed, drill spindleassembly 22 is stationary during any drilling cycles being performed.Shaft 26 and drill bit 24 rotate, but preferably remain stationary inthe axial direction during any drilling cycles being performed. Instead,the lens blank is preferably retained within a clamping carriageproviding on processing device 10 which is moveable toward and away fromdrill bit 24, as known in the art. In this way, the lens blank may bemoved toward and away from processing tools, such as a router tool ordrill bit 24.

Processing device 10 also preferably includes a probe assembly formeasuring the curvature of the lens blank, such as provided on theNational Optronic's 7E Patternless Edger machine. As known in the art,the probe assembly includes a probe for measuring the distance betweenthe carriage in an initial position and various locations on the lensblank. The overall shape of the lens blank is known from the trace data,which may be recalled from storage by the CPU. The curvature of lensblank may be determined based upon the variations in distance measuredby the probe.

Once the curvature and shape of the lens blank are determined, thecarriage and thus the lens blank retained therein may be moved towardand away from rotating drill bit 24 during a drill cycle. The relativemovement between the lens blank and a distal end 36 of drill bit 24, ordrill depth, during a particular drill cycle therefore depends upon theshape and curvature of lens blank. For example, as shown in FIG. 4, afirst drill depth D1 may be required for drilling a first hole H1 (shownin phantom) in a lens blank L. A second drill depth D2, which is lessthan drill depth D1 measured from a plane P along which distal end 36 isdisposed, may be required for drilling a second hole H2 (shown inphantom) disposed in a different location. The CPU determines the properdrill depth for a particular drill cycle depending on the location ofthe hole being drilled relative to the shape of lens blank L, which isknown from the trace data. Proper drill depth is also determined basedupon the curvature of lens blank L, as determined by the probe providedin processing device 10.

The carriage in which the lens blank is retained in processing device 10is moveable horizontally as well as vertically relative to drill bit 24.As noted above, one drill bit, such as drill bit 24, may be used to cutholes of variable diameter. Drill bit 24 has a defined diameter, andtherefore a hole formed by drill bit 24 has a diameter at least as largeas the diameter of drill bit 24. For example, drill bit 24 may have adiameter of about 1 mm, and a length of about 8 mm. The diameter of thehole being drilled may be increased by moving lens blank L in agenerally circular motion when drill bit 24 is disposed within the holebeing formed. For example, coordinated movement of the carriage on whichlens blank L is retained while drill bit 24 is disposed within a newlyformed hole results in a hole having a diameter larger than the diameterof drill bit 24.

Movement of the carriage is controlled by the CPU. The CPU operablycauses processing device 10 to process lens blank L according toparticular processing parameters.

Referring again to FIG. 1, processing device 10 preferably includes acontrol panel 38 mounted to an upper portion thereof which providesaccess by the technician to various controls, collectively 40.Processing parameters may be input into processing device 10 viacontrols 40. Controls 40 may be provided as a touch screen including aplurality of touch keys and input fields displayed thereon.Alternatively, a conventional keypad or other input device may beprovided. Alternatively, an external input device operably associatedwith processing device 10 may be provided, such as a tablet or keypad.

Processing device 10 may also include a display 42 for displaying inputfields, trace data, and other information corresponding to theprocessing parameters. As shown in FIG. 1, display screen 42 is an LCDdisplay screen mounted on an upper portion of processing device 10.However, an external display operably associated with processing device10 may be provided.

Processing parameters may provide for one or more holes to be drilled ina lens blank. Various input fields may be provided, which are displayedon display screen 42, such as an input field for selecting an expectedor desired number of holes to be drilled in lens blank, an input fieldfor selecting the location of each hole, and an input field forselecting the diameter of each hole. As noted above, drill depth ispartially dependent on the shape and curvature of the lens blank beingdrilled, which is calculated by the CPU based upon the parametersselected by the technician, trace data, and curvature measurements.

Input fields may prompt the technician to enter numerical datacorresponding to the number of holes desired, the diameter of each hole,and the location of each hole. The CPU may recall trace data relating tothe shape of the lens blank in order to ensure proper placement of eachhole thereon. The CPU locates and then drill the hole(s) at the selectedposition(s) based on the shape of the lens blank which is known from thetrace data, as described more fully in Applicant's co-pendingapplication Ser. No. 11/511,431, titled “Method Of Grooving and Drillingan Ophthalmic Lens Blank, Machine Programmed Therefor, and ComputerProgram”, filed Aug. 29, 2006, the disclosure of which is incorporatedherein by referenced.

The desired shape of the resulting lens may also be provided by theframe manufacturer, and downloaded to the CPU via as associated serialport. Such trace data is often accessible by the frame manufacturer'smodel number and size information, and may be easily downloaded to theCPU. Trace data may be stored on the associated storage medium andrecalled by the CPU when needed. Accordingly, the technician may requestparticular stored or downloaded trace data via an associated input fieldvia controls 40.

As noted above and shown in FIG. 4, the drill depth required to form ahole depends partially on the shape and curvature of the particular lensblank being drilled. Processing device is preferably calibrated foroptimal drill depth, wherein the lens blank extends toward drill bit 24a sufficient distance such that distal end 36 of drill bit 24 extendscompletely through the lens blank, but without extending substantiallybeyond this distance. Optimal drill depth between distal end 36 and thelens blank is therefore just enough to properly form the hole during thecorresponding drill cycle.

The CPU calculates the distance between distal end 36 of drill bit 24and the lens blank. The shape of the lens blank is known from the tracedata, and the thickness and curvature of the lens blank are determinedby the probe. As noted above, drill bit 24 is maintained in a fixedposition in the axial direction, which is known to the CPU. The CPUtherefore calculates the distance between distal end 36 and the lensblank based upon this information in order to determine optimal drilldepth for a particular drill cycle.

Drill depth calculation is therefore partially dependent upon theposition of distal end 36. If the orientation of distal end 36 relativeto the carriage retaining the lens blank is altered, re-calibration ofthe calculations performed by the CPU may be required. For example, ifdrill bit 24 is replaced with a new drill bit having a longer or shorterlength, the position of the distal end of the new drill bit will not bein a position ‘known’ by the CPU, resulting in faulty drill depthcalculations. Rather, the CPU will continue to calculate drill depthbased upon the position of the replaced drill bit 24. Likewise, if theprobe assembly or carriage assembly are replaced, or their positionsrelative to drill bit 24 altered, drill depth calculations will be basedupon incorrect data.

If drill depth is too short during a particular drill cycle, distal end36 of drill bit 24 fails to contact, or fails to extend completelythrough, the lens blank. Given the size of the hole(s) being formed, itis not always obvious to the technician whether proper hole formationhas been achieved. If drill depth is too long, distal end 36 continuesto extend beyond the lens blank an unnecessarily long distance. Anexcessive drill depth increases the possibility of damage to the lensblank, and increases processing time.

Conventional techniques of re-calibrating drill depth required thetechnician to estimate the increase or decrease required, and input theestimated new values for drill depth for a particular cycle. Thetechnician would then test the estimated values, and re-estimate anadditional increase or decrease if needed, depending on the outcome ofthe test. Such techniques are tedious and time consuming.

The disclosed method of re-calibrating drill depth will be describedwith reference to FIG. 5. As described above, the lens blank is securedwithin the carriage of processing device 10, and drilling mechanism 12is positioned in the drilling position proximate the lens blank. The CPUrecalls trace data for the particular lens blank from the associatedstorage memory at S1. Trace data typically includes a list of pointsthat define the shape of the lens and matching frame. The curvature ofthe lens is determined by the probe assembly at S2, and the resultingmeasurements are communicated to the CPU.

Then, the technician selects a number of drill cycles for drilling anexpected number of holes in the lens blank at S3. The number of drillcycles need not equal the expected number of holes that will actually bedrilled in lens blank L. Preferably, the expected number of holes thatwill be formed in the lens blank is less than the selected number ofdrill cycles. Therefore, distal end 36 should be spaced from and fail tocontact the lens blank during at least one of the drill cycles. Forexample, the technician may select that six drill cycles be performed,with three holes expected to be drilled.

An exemplary input screen 100 showing various input fields is shown inFIG. 6. As described above, the technician may enter and/or alter valuesin each input field via controls 40. Drill data for six drill cycles isprovided in input fields in the lower central portion of the screen,including input fields for horizontal and vertical positions, and holediameter. Above the drill data input fields, the periphery of the lensto be drilled is displayed, which shows the position of the six drillcycles relative to the lens shape. Trace data and other edginginformation is also displayed, and may be adjusted, in the input fieldsdisposed on the left hand side of the screen. Although drill data forsix cycles has been entered, distal end 36 of drill bit 24 is expectedto contact the lens blank only three times, as shown in the “drill touchcount” input field provided in the upper right portion of the displayscreen.

Referring again to FIG. 5, the selected number of drill cycles is thenperformed by processing device 10 at S4. For example, six drill cyclesmay be performed at selected positions 1-6 relative to the lens blank,as shown in FIG. 7A. A hole is drilled during each drill cycle at aparticular location based upon selected processing parameters input bythe technician, and based upon the shape and curvature of the lensblank. The drill depth of each consecutive drill cycle varies,preferably incrementally. The drill depth of each consecutive drillcycle may incrementally decrease or increase by a defined amount. Forexample, the drill depth may increase, or decrease, by about 0.1 mmduring each consecutive drill cycle.

Then at S5, the actual number of times distal end 36 contacted thesurface of the lens blank during the drill cycles performed at S4 iscompared to the expected number of holes selected at S3. The technicianenters the resulting number of contacts into processing device 10 viacontrols 40. If the actual number of contacts corresponds to theexpected number of holes, no adjustment is required.

If the actual number of contacts is more than the expected number ofholes, drill depth is decreased at S6. The amount drill depth isdecreased may correspond to the number of times distal end 36 contactedthe surface of lens blank. The greater the difference between thecontact number and the expected number, the more drill depth isdecreased. For example, the CPU will decrease drill depth a greateramount if distal end 36 contacted the lens blank six times, compared tothe amount of decrease if the distal end 36 had contacted the lens blankfour times. The amount of decrease may be a predetermined amount foreach contact number above the expected number.

If the actual number of contacts is less than the expected number ofholes, drill depth is increased at S7. The greater the differencebetween expected number and the contact number, the more drill depth isincreased. The amount of increase may be a predetermined amount for eachdrill cycle that was expected but failed to contact the lens blank. Asshown in FIG. 7B, three holes were expected to be drilled in the sixdrill cycles selected by the technician (shown in FIG. 7A). However,only two holes were actually formed in the lens blank at positions 4 and5. The technician enters the number of holes actually formed via control40. The CPU re-calibrates the distance between the lens blank and distalend 36 by increasing this distance, thereby effectively re-calibratingthe position of distal end 24 relative to the lens blank. The CPU againperforms the requested six drill cycles, which this time result in threeholes 4, 5 and 6 being formed due to the implementation of an increaseddrill depth, as shown in FIG. 7C.

The position of distal end 36 is thereby re-established. The CPU maythen re-calibrate optimal drill depth for any drill cycle based on theoptimal drill depth determined during the test drill cycles performed,given the orientation of distal end 36 relative to the carriageretaining the lens blank has been re-established. Drill depth isadjusted and re-calibrated to ensure that the lens blank contacts drillbit 24 and distal end 36 extends through the lens blank just enough toform the hole during the corresponding drill cycle, without extending anexcessive distance beyond the lens blank.

The CPU may re-calibrate drill depth by applying an algorithm whichincreases or decreases existing drill depth values stored in theassociated memory by a predetermined amount corresponding to the drilldepth deviation determined during the test cycles. An exemplary computerroutine for re-calibrating drill depth according to the method disclosedabove is provided in computer program listing Appendix A. However, itwould be readily understood that other computer routines may be appliedto achieve the disclosed method. Each drill depth value may beassociated with a particular drilling instruction set provided in acomputer program, which operably causes an associated drill cycle to beperformed by processing device 10. The computer program may be stored ona medium in communication with the CPU, and initiated by the CPU inresponse to a command from a user via associated controls 40. Thecomputer program automatically re-calibrates all drill depths associatedwith each of the drilling instruction sets by either increasing ordecreasing drill depth.

The present invention is also directed to a method of calibrating drillhole diameter. As noted above, drill bit 24 may be used to cut holes ofvariable diameter in a lens blank. Drill bit 24 has a defined diameter,which is known to the CPU. In order to form a hole having a diameterlarger than the diameter of drill bit 24, the carriage in which the lensblank is retained is moved in a circular motion when drill bit 24 isdisposed within the hole being formed. The CPU operably causescoordinated movement of the carriage and/or associated moveable tableson which the carriage is disposed. If the carriage and/or drill bit 24are replaced, the same coordinated movement controlled by the CPU mayresult in a hole having an unintended diameter. For example, if drillbit 24 is replaced with a new drill bit, the new drill bit may have adifferent diameter or rotate slightly different than the previous drillbit 24. This deviation may result in a hole diameter larger or smallerthan intended. Thus, the CPU may periodically need to be re-calibratedto account for such deviations.

Thus, it may be desirable to ensure that the hole diameter selected bythe technician is the hole diameter actually formed by processing device10, particularly when drill bit 24 or other components of processingdevice 10 have been replaced or adjusted. Calibration of drill hole sizeensures proper functioning of processing device 10.

The disclosed method of re-calibrating drill hole diameter will bedescribed with reference to FIG. 8. As described above, the lens blankis secured within the carriage of processing device 10, and drillingmechanism 12 is positioned in the drilling position proximate the lensblank. The CPU recalls trace data for the particular lens blank from theassociated storage memory at S1. The curvature of the lens is determinedby the probe assembly at S2, and the resulting measurements arecommunicated to the CPU. Then at S3, the technician selects a number ofdrill cycles for drilling a plurality of holes in the lens blank havingdiameters that vary incrementally. The technician selects a base holesize which is equal to the hole diameter expected to be formed duringone of the selected drill cycles at S4. Preferably, the base hole sizeis a value intermediate the range of hole diameters expected to beformed during the selected drill cycles.

Next, the selected number of drill cycles are performed at S5. A hole isdrilled during each drill cycle at a particular location selected by thetechnician, and based upon the shape and curvature of the lens blank.Holes are formed during the drill cycles of variable diameter.Preferably, the diameter of each consecutive hole formed increases ordecreases incrementally by a predetermined amount. For example, sixholes may be drilled, with the expected hole diameter of a first drillcycle being 1.48 mm, the expected hole diameter of the second drillcycle being 1.49 mm, the expected hole diameter of the third drill cyclebeing 1.50 mm, the expected hole diameter of the fourth drill cyclebeing 1.51 mm, the expected hole diameter of the fifth drill cycle being1.52, and the expected hole diameter of the sixth drill cycle being1.53. The selected base hole size is preferably intermediate thesmallest and largest diameter values. For example, a base hole size of1.50 mm may have been selected.

The technician then measures the actual diameter of each hole formed atS6. Pin gauges may be used to determine the precise diameter of eachhole formed. As known in the art, pin gauges are precision sizedcylinders having a known diameter which may be used for measuring theinner diameter of cylindrical holes.

The technician then selects the drill cycle that formed a hole having anactual diameter corresponding to the base hole size at S7, which may beany one of the drill cycles performed. The expected diameter initiallyassociated with the selected drill cycle is adjusted to conform with thebase hole size.

If the expected diameter of the selected drill cycle is less than thebase hole size, expected drill hole diameter is increased at S8. Forexample, the second drill cycle may have been selected as the drillcycle that formed an actual diameter corresponding to the base hole sizeof 1.50 mm, despite the second drill cycle expected to form a holehaving a diameter size of 1.49 mm. The selected drill cycle iscommunicated to the CPU via controls 40. The CPU then adjusts drilldiameter size by increasing the expected diameter of all drill cycles by0.01 mm.

If the expected diameter of the selected drill cycle is more than thebase hole size, expected drill hole diameter is decreased at S9. Forexample, the fifth drill cycle may have been selected as the drill cyclethat formed an actual diameter corresponding to the base hole size of1.50 mm, despite the fifth drill cycle expected to form a hole having adiameter size of 1.52 mm. The selected drill cycle is communicated tothe CPU via controls 40. The CPU then adjusts drill diameter size bydecreasing the expected diameter of all drill cycles by 0.02 mm. Oncethe deviation between the expected hole diameter and actual holediameter is determined, the CPU may re-calibrate all expected holediameters.

An exemplary input screen 200 showing various input fields is shown inFIG. 9. As described above, the technician may enter and/or alter valuesin each input field via controls 40. Similar to input screen 100, drilldata for six drill cycles is provided in input fields in the lowercentral portion of the screen, including input fields for horizontal andvertical positions, and hole diameter. Above the drill data inputfields, the periphery of the lens to be drilled is displayed, whichshows the position of the six drill cycles relative to the lens shape.Trace data and other edging information is also displayed, and may beadjusted, in the input fields disposed on the left hand side of thescreen. The input screen indicates that “Drill Size Calibration” isbeing performed, as shown in the upper right portion of the displayscreen. In addition, an input field for selected “Size” for drillcalibration is provided, along with an input field for a desired “BaseHole Size”. The technician selects which of the six drill cycles wasclosest to the base hole size in input field “Best Size Match”.

The CPU may re-calibrate hole diameters associated with drill cycles byapplying an algorithm which adjusts the existing expected hole diametervalues stored in the associated memory by a predetermined amountcorresponding to the expected hole diameter deviation determined duringthe test cycles. An exemplary computer routine for re-calibrating holediameter size according to the method disclosed above is provided incomputer program listing Appendix A. However, it would be readilyunderstood that other computer routines may be applied to achieve thedisclosed method. Each hole diameter value may be associated with aparticular drilling instruction set providing in a computer program,which operably causes an associated drill cycle to be performed byprocessing device 10 that forms a hole having a predetermined diameterdefining a hole size. The computer program may be stored on a medium incommunication with the CPU, and initiated by the CPU in response to acommand from a user via associated controls 40. The computer programautomatically re-calibrates all hole sizes associated with each of thedrilling instruction sets by either increasing or decreasing hole size.

It will be apparent to one of ordinary skill in the art that variousmodifications and variations can be made to the disclosed inventionwithout departing from the spirit of the invention. Therefore, it isintended that the present invention include all such modifications orvariations, provided they come within the scope of the following claimsand their equivalents.

1. A method of calibrating drill depth of an ophthalmic processingdevice, comprising the steps of: providing a lens blank; utilizing aprocessing device having a drill bit for drilling holes in the lensblank, one of the drill bit and the lens blank being moveable during adrill cycle toward and away from the other a predetermined distancedefining a drill depth; selecting a number of drill cycles for drillingan expected number of holes in the lens blank; performing the selectednumber of drill cycles, wherein the drill depth of each consecutivedrill cycle varies incrementally; comparing an actual number oflocations the drill bit contacted the lens blank during said performingstep to the expected number of holes; decreasing the drill depth if theactual number of holes is more than the expected number of holes; andincreasing the drill depth if the actual number of holes is less thanthe expected number of holes.
 2. The method of claim 1, wherein thedrill depth of each consecutive drill cycle incrementally decreasesduring said performing step.
 3. The method of claim 1, wherein theexpected number of holes is less than the selected number of drillcycles during said selecting step.
 4. The method of claim 3, wherein adistal end of the drill bit is spaced from the lens blank during atleast one of the drill cycles during said performing step.
 5. The methodof claim 4, wherein the distal end of the drill bit extends into thelens blank during at least one of the drill cycles during saidperforming step.
 6. The method of claim 1, wherein the processing devicedecreases the drill depth by a predetermined distance if the actualnumber of holes is more than the expected number of holes during saiddecreasing step.
 7. The method of claim 1, wherein the processing deviceincreasing the drill depth by a predetermined distance if the actualnumber of holes is less than the expected number of holes during saidincreasing step.
 8. A method of calibrating an ophthalmic processingdevice used to cut holes of variable diameter in a lens blank,comprising the steps of: providing a lens blank; utilizing a processingdevice for drilling holes in the lens blank during drill cycles;selecting a base hole size having a predetermined diameter; selecting anumber of drill cycles for forming a corresponding number of holeshaving expected diameters that vary incrementally; performing theselected number of drill cycles; comparing actual diameters of holesformed during the performed drill cycles to the predetermined diameter;selecting one of the number of drill cycles that formed the hole havingthe actual diameter corresponding to the predetermined diameter;adjusting the expected diameter of the selected one of the number drillcycles to conform to the predetermined diameter.
 9. The method of claim8, including the further step of calibrating the expected diametersassociated with the drill cycles by an adjustment value required toconform the expected diameter of the selected one during said adjustingstep.
 10. The method of claim 8, including the further step of measuringthe actual diameter of each hole formed after said performing step. 11.The method of claim 10, including the step of using pin gauges duringsaid measuring step.
 12. A processing device programmed to drill holesin an ophthalmic lens blank, comprising: a processing device having adrill bit for drilling holes in a lens blank and a carriage forretaining the lens blank, one of said drill bit and said carriagemoveable toward and away from the other during a drill cycle; a centralprocessing unit operably associated with said processing device forcontrolling operation thereof; a user interface in communication withsaid central processing unit for receiving and transmitting commandsfrom a user to said central processing unit; and a computer programstored on a medium in communication with said central processing unit,said computer program comprising: a) a plurality of drilling instructionsets, each of said drilling instruction sets operably causing one ofsaid drill bit and said carriage to move toward the other by apredetermined distance defining a drill depth, wherein the drill depthassociated with each of said drilling instruction sets varies; b) acalibration instruction set that compares an expected number of contactsbetween the drill bit and the lens blank with an actual number ofcontacts between the drill bit and the lens blank after said pluralityof drilling instruction sets are performed and adjusts each of saiddrill depths based on the comparison.
 13. The processing device of claim12, wherein said calibration instruction set increases said drill depthswhen the number of actual contacts is less than the number of expectedcontacts.
 14. The processing device of claim 12, wherein saidcalibration instruction set decreases said drill depths when the numberof actual contacts is greater than the number of expected contacts. 15.A processing device programmed to drill holes in an ophthalmic lensblank, comprising: a processing device having a drill bit for drillingholes in a lens blank of variable size; a central processing unitoperably associated with said processing device for controllingoperation thereof; a user interface in communication with said centralprocessing unit for receiving and transmitting a base hole size from auser; and a computer program stored on a medium in communication withsaid central processing unit, said computer program comprising: a) aplurality of drilling instruction sets, each of said drillinginstruction sets operably causing said processing device to form a holehaving a predetermined diameter defining a hole size, wherein the holesizes associated with each of said drilling instruction sets variesdependent on the base hole size; b) a calibration instruction set thatreceives an input from a user selecting a drilling instruction set thatformed a hole closest in size to the base hole size and adjusts each ofthe remaining drilling instruction sets to equal the selected drillinginstruction set.
 16. The processing device of claim 15, wherein saidcalibration instruction set increases said hole sizes.
 17. Theprocessing device of claim 15, wherein said calibration instruction setdecreases said hole sizes.
 18. A computer program stored on a medium foruse in a drilling process employing a lens blank and a processingdevice, the computer program comprising: a plurality of drillinginstruction sets, each of said drilling instruction sets operablycausing one of a lens blank and a drill bit associated with a processingdevice to move toward the other by a predetermined distance defining adrill depth, wherein the drill depth associated with each of saiddrilling instruction sets varies; a calibration instruction set thatcompares an expected number of contacts between the drill bit and thelens blank with an actual number of contacts between the drill bit andthe lens blank after said plurality of drilling instruction sets areperformed and adjusts each of said drill depths based on the comparison.19. The computer program of claim 18, wherein said calibrationinstruction set increases said drill depths when the number of actualcontacts is less than the number of expected contacts.
 20. The computerprogram of claim 18, wherein said calibration instruction set decreasessaid drill depths when the number of actual contacts is more than thenumber of expected contacts.
 21. A computer program stored on a mediumfor use in a drilling process employing a lens blank and a processingdevice, the computer program comprising: a plurality of drillinginstruction sets, each of said drilling instruction sets operablycausing a processing device to form a hole having a predetermineddiameter defining a hole size, wherein the hole sizes associated witheach of said drilling instruction sets varies dependent on a base holesize input by a user; a calibration instruction set that receives aninput from a user selecting a drilling instruction set that formed ahole closest in size to the base hole size and adjusts each of theremaining drilling instruction sets to equal the selected drillinginstruction set.
 22. The computer program of claim 21, wherein saidcalibration instruction set increases said hole sizes.
 23. The computerprogram of claim 21, wherein said calibration instruction set decreasessaid hole sizes.